Communication method, communication device, communication system and computer readable medium

Abstract

The invention discloses a communication method, a communication device, a communication system and a computer readable medium, and relates to the technical field of wireless communication, and the method comprises the steps: obtaining a channel real-time change parameter and a channel real-time change coefficient sent by a ground control center; determining a current cyclic prefix length based on the channel real-time change parameter and the channel real-time change coefficient; modifying the prefix length of an orthogonal frequency division multiplexing symbol by using the current cyclic prefix length to obtain a new orthogonal frequency division multiplexing symbol; and sending the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new orthogonal frequency division multiplexing symbol based on the current cyclic prefix length to obtain communication data. According to the invention, the reliability of communication can be improved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and is particularly applicable to satellite communication, space-ground integrated networks and spacecraft OFDM communication systems. Specifically, it relates to a communication method, communication device, communication system and computer-readable medium. Background Technology

[0002] With the continuous development of satellite communication technology, satellite communication, space-ground integrated networks, and communication between spacecraft are mainly carried out through Orthogonal Frequency Division Multiplexing (OFDM). When using OFDM technology for communication, a cyclic prefix (CP) length is usually used to deal with the delay spread of the channel.

[0003] However, when using CP length to address channel delay spread, there is a problem of low communication reliability. Summary of the Invention

[0004] This invention aims to address, to a certain extent, one of the technical problems in related technologies. To this end, this invention provides a communication method, communication device, communication system, and computer-readable medium, which have the advantage of improving communication reliability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A communication method for an on-board processing unit, comprising:

[0007] The system acquires real-time channel change parameters and real-time channel change coefficients sent by the ground control center; wherein, the real-time channel change parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit, and the real-time channel change coefficients include a distance delay coefficient and a velocity coefficient.

[0008] The current cyclic prefix length is determined based on the real-time channel change parameters and the real-time channel change coefficients.

[0009] The prefix length of the orthogonal frequency division multiplexing symbol is modified using the current cyclic prefix length to obtain a new orthogonal frequency division multiplexing symbol;

[0010] The current cyclic prefix length and the new orthogonal frequency division multiplexing (OFDM) symbol are sent to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new OFDM symbol based on the current cyclic prefix length to obtain communication data.

[0011] Optionally, the step of determining the current cyclic prefix length based on the real-time channel variation parameters and the real-time channel variation coefficients includes:

[0012] The current cyclic prefix length is determined based on the real-time channel change parameters, the real-time channel change coefficients, and Formula 1.

[0013] Formula 1 includes:

[0014]

[0015] Among them, CP length The current loop prefix length is represented by α, the distance delay coefficient by β, the velocity coefficient by d, the communication distance by |Δv|, and the radial velocity difference by f. c Indicates carrier frequency, c represents the speed of light, and Base... CP Indicates the base CP length.

[0016] Optionally, the step of sending the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit includes:

[0017] The current cyclic prefix length is encoded to obtain the cyclic prefix pattern identifier;

[0018] The prefix mode identifier is stored in the physical frame header, and the physical frame header and the new orthogonal frequency division multiplexing symbol are sent to the terminal adaptation unit.

[0019] Optionally, the physical frame header includes a pilot group, a prefix mode identifier, and a distance check code.

[0020] Optionally, after sending the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, the method further includes:

[0021] Determine the relative speed between the terminal adaptation unit and the on-board processing unit;

[0022] The pre-compensation frequency offset is determined using the relative velocity.

[0023] The frequency of the pilot signal is adjusted using the pre-compensated frequency offset, and the adjusted pilot signal is sent to the terminal adaptation unit so that the terminal adaptation unit can determine the residual frequency offset based on the adjusted pilot signal. The terminal adaptation unit encapsulates the residual frequency offset into a feedback report and sends the feedback report to the on-board processing unit.

[0024] Receive feedback reports sent by the terminal adaptation unit;

[0025] The feedback report is sent to the ground control center so that the ground control center can parse the feedback report to obtain the residual frequency offset, determine a new subcarrier spacing based on the residual frequency offset and the current subcarrier spacing, calculate a new cyclic prefix length based on the new subcarrier spacing, and send the new cyclic prefix length to the on-board processing unit.

[0026] The new cyclic prefix length is received and sent to the terminal adaptation unit.

[0027] Optionally, the new subcarrier spacing range is This indicates the new subcarrier spacing.

[0028] Optionally, after sending the current cyclic prefix length and the new orthogonal frequency division multiplexing (OFDM) symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new OFDM symbol based on the current cyclic prefix length to obtain communication data, the method further includes:

[0029] Receive the bit error rate sent by the terminal adaptation unit;

[0030] The bit error rate is sent to the ground control center so that after receiving the bit error rate, the ground control center determines whether the bit error rate is greater than a preset bit error rate. If the bit error rate is greater than the preset bit error rate, the long short-term memory model is optimized using historical channel data and current channel data to obtain new real-time channel change coefficients. The new real-time channel change coefficients are then converted into special subframe configuration indexes and sent to the on-board processing unit.

[0031] Receive the special subframe configuration index;

[0032] The new real-time channel change coefficients are determined based on the special subframe configuration index.

[0033] In a second aspect, the present invention also provides a communication device for an on-board processing unit, comprising:

[0034] The acquisition module is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center; wherein, the real-time channel change parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit, and the real-time channel change coefficients include a distance delay coefficient and a velocity coefficient;

[0035] The determination module is used to determine the current cyclic prefix length based on the real-time channel change parameters and the real-time channel change coefficients;

[0036] The modification module is used to modify the prefix length of the orthogonal frequency division multiplexing symbol using the current cyclic prefix length, so as to obtain a new orthogonal frequency division multiplexing symbol;

[0037] The sending module is used to send the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new orthogonal frequency division multiplexing symbol based on the current cyclic prefix length to obtain communication data.

[0038] Thirdly, the present invention also provides a communication system, including a satellite-ground cooperative system, one or more processors, a memory, and one or more programs, wherein the satellite-ground cooperative system includes an on-board processing unit, a ground control center, and a terminal adaptation unit.

[0039] The ground control center is used to send real-time channel variation coefficients to the on-board processing unit;

[0040] The terminal adaptation unit is used to receive the current cyclic prefix length sent by the on-board processing unit, and remove the prefix length of the new orthogonal frequency division multiplexing symbol according to the current cyclic prefix length to obtain communication data;

[0041] The on-board processing unit is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center. Based on the real-time channel change parameters and real-time channel change coefficients, it determines the current cyclic prefix length, modifies the prefix length of the orthogonal frequency division multiplexing (OFDM) symbol using the current cyclic prefix length, obtains a new OFDM symbol, and sends the current cyclic prefix length and the new OFDM symbol to the terminal adaptation unit.

[0042] The one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for implementing any of the preceding communication methods.

[0043] Fourthly, the present invention also provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the communication method described in any of the preceding claims.

[0044] In related technologies, during data communication, to combat inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by multipath propagation, and to provide a guard interval for multipath signals to ensure that the receiver can correctly demodulate each subcarrier signal, the technique used is to add a fixed-length copy signal, identical to the tail of the OFDM symbol, before the OFDM symbol. This is known as adjusting the OFDM prefix length using a fixed CP length. However, adjusting the OFDM prefix length with a fixed CP length cannot flexibly adapt to changes in multipath delay under different scenarios. Specifically, when the actual multipath delay exceeds the CP length, the interference suppression effect decreases; conversely, an excessively long CP wastes spectrum resources and reduces transmission efficiency.

[0045] Based on this, when adjusting the OFDM prefix length using the CP length, this invention adaptively adjusts the current cyclic prefix length by utilizing the communication distance and radial velocity difference between the on-board processing unit and the terminal adaptation unit, and then adjusts the prefix length of the orthogonal frequency division multiplexing (OFDM) symbols using the current cyclic prefix length. Since the current cyclic prefix length of this invention is adjusted in real-time based on the communication distance and radial velocity difference between the on-board processing unit and the terminal adaptation unit, adjusting the OFDM prefix length using the current cyclic prefix length can better solve the symbol spacing interference problem caused by high dynamic range, Doppler shift, and time delay differences. This avoids the phenomenon that interference suppression effectiveness decreases when the actual multipath delay exceeds the CP length; while an excessively long CP would waste spectrum resources and reduce transmission efficiency, thereby improving the reliability and spectral efficiency of data communication.

[0046] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. The preferred embodiments or means of the present invention will be shown in detail in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of the present invention. In addition, each of these features, elements and components appearing in the following text and drawings is a plurality of, and different symbols or numbers are used for convenience of representation, but all represent parts with the same or similar construction or function. Attached Figure Description

[0047] The present invention will be further described below with reference to the accompanying drawings:

[0048] Figure 1 A flowchart illustrating one embodiment of the communication method provided by the present invention;

[0049] Figure 2 This is a schematic diagram illustrating the specific process of sending the current cyclic prefix length to the terminal adaptation unit provided by the present invention.

[0050] Figure 3This is a schematic diagram of the process for calculating the new cyclic prefix length using residual frequency offset update provided by the present invention;

[0051] Figure 4 This is a schematic diagram of the dual-ring compensation process provided by the present invention;

[0052] Figure 5 This is a schematic diagram of the process for updating the real-time channel change coefficient based on the bit error rate provided by the present invention.

[0053] Figure 6 This is a schematic diagram of the dynamic cyclic prefix adjustment process provided by the present invention;

[0054] Figure 7 This is a schematic diagram of the framework of the space-ground cooperative system provided by the present invention. Detailed Implementation

[0055] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain the present invention and should not be construed as limiting the invention.

[0056] The terms "an embodiment," "example," or "trademark" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this invention. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0057] As a first aspect of the present invention, a communication method is provided, such as... Figure 1 As shown, the method includes:

[0058] In step S110, the real-time channel change parameters and the real-time channel change coefficients sent by the ground control center are obtained.

[0059] The real-time channel variation parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit. The real-time channel variation coefficients include a distance delay coefficient and a velocity coefficient.

[0060] In this embodiment, the on-board processing unit can be a high-performance data processing device deployed on a satellite.

[0061] Specifically, the ground control center locally stores historical channel data containing characteristic information such as channel signal strength and delay spread. The ground control center can input this historical channel data into a Long Short-Term Memory (LSTM) network model, which excels at handling time-series dependencies, for training. Through backpropagation, the coefficients α and β are iteratively optimized to obtain optimized coefficients α and β. Coefficient α is used to control the influence of range-dependent delay, and β is used to control the influence of velocity-dependent Doppler residuals; that is, coefficient α is used as the range delay coefficient, and coefficient β is used as the velocity coefficient. After obtaining the optimized coefficients α and β, they can be encoded to obtain a special subframe configuration index, which is then sent to the onboard processing unit via the satellite uplink.

[0062] The on-board processing unit stores a mapping table, which contains the mapping relationships between indices and coefficients α and β. Upon receiving a special subframe configuration index, the on-board processing unit can look up the mapping table based on the index to determine coefficients α and β, thus determining the real-time channel variation coefficients. After determining the real-time channel variation coefficients, the on-board processing unit can use dual-frequency GNSS (Global Navigation Satellite System) to determine the communication distance with the terminal adaptation unit and combine this with Doppler radar measurements of the radial velocity difference between itself and the terminal adaptation unit.

[0063] In step S120, the current cyclic prefix length is determined based on the channel real-time change parameters and the channel real-time change coefficients.

[0064] Specifically, after obtaining the real-time channel variation parameters and coefficients, the on-board processing unit can determine the current cyclic prefix length based on these parameters and Formula 1. Formula 1 includes: Among them, CP length The current loop prefix length is represented by α, the distance delay coefficient by β, the velocity coefficient by d, the communication distance by |Δv|, and the radial velocity difference by f. c Indicates carrier frequency, c represents the speed of light, and Base... CP This indicates the base CP length, which defaults to 0.2 μs.

[0065] In step S130, the prefix length of the orthogonal frequency division multiplexing symbol is modified using the current cyclic prefix length to obtain a new orthogonal frequency division multiplexing symbol.

[0066] In step S140, the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol are sent to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new orthogonal frequency division multiplexing symbol based on the current cyclic prefix length to obtain communication data.

[0067] After calculating the current cyclic prefix length based on the channel real-time change parameters, the channel real-time change coefficients, and Formula 1, the on-board processing unit can use the current cyclic prefix length to modify the prefix length of the orthogonal frequency division multiplexing (OFDM) symbol, obtain a new OFDM symbol, and send the new OFDM symbol and the current cyclic prefix length to the terminal adaptation unit via the satellite downlink.

[0068] In related technologies, during data communication, to combat inter-symbol interference (ISI) and inter-subcarrier interference (ICI) caused by multipath propagation, and to provide a guard interval for multipath signals to ensure that the receiver can correctly demodulate each subcarrier signal, the technique used is to add a fixed-length copy signal, identical to the tail of the OFDM symbol, before the OFDM symbol. This is known as adjusting the OFDM prefix length using a fixed CP length. However, adjusting the OFDM prefix length using a fixed CP length cannot flexibly adapt to changes in multipath delay under different scenarios. Specifically, when the actual multipath delay exceeds the CP length, the interference suppression effect decreases; conversely, an excessively long CP wastes spectrum resources and reduces transmission efficiency.

[0069] Based on this, this embodiment, when adjusting the OFDM prefix length using the CP length, adaptively adjusts the current cyclic prefix length by utilizing the communication distance and radial velocity difference between the on-board processing unit and the terminal adaptation unit, and adjusts the prefix length of the orthogonal frequency division multiplexing symbol using the current cyclic prefix length, as shown in Table 1 below. Since the current cyclic prefix length of this invention is adjusted in real time based on the communication distance and radial velocity difference between the on-board processing unit and the terminal adaptation unit, the cyclic prefix length ranges from 1 to 5 μs for short-range communication scenarios between satellites or between near-Earth satellites and the ground; from 5 to 20 μs for medium-range communication scenarios between low Earth orbit (LEO) satellites and the ground; and from 20 to 50 μs for long-range communication scenarios between geostationary orbit (GEO) satellites and deep space. Adjusting the prefix length of orthogonal frequency division multiplexing (OFDM) based on different current cyclic prefix lengths according to the communication scenario can better solve the symbol spacing interference problem caused by high dynamic distance, Doppler frequency shift, and time delay differences. This avoids the phenomenon that interference suppression effect will decrease when the actual multipath delay exceeds the CP length; while an excessively long CP will waste spectrum resources and reduce transmission efficiency, thereby improving the reliability and spectrum efficiency of data communication.

[0070] Table 1

[0071]

[0072] In addition, this embodiment selects different cyclic prefix lengths according to the communication scenario. In short-range communication scenarios, the overhead of the cyclic prefix is ​​reduced by 70%, and the overall spectrum utilization is improved by 15% to 25%. Furthermore, by dynamically adjusting the cyclic prefix length, the retransmission rate can be reduced, and the end-to-end latency is reduced by 30%. Simultaneously, this embodiment also has extremely high compatibility, supporting not only 5G or 6G satellite access under the 3rd Generation Partnership Project (3GPP) Non-Terrestrial Network (NTN) standard, but also existing Low Density Parity Check Code (LDPC) encoding and frame structures. This embodiment can also be deployed on low-Earth orbit constellations such as Starlink and BeiDou-3, as well as deep space exploration missions (such as the Chang'e lunar exploration program), solving communication reliability issues under high dynamic distances and providing underlying support technology for 6G integrated space-ground networks.

[0073] When sending the current cyclic prefix length to the terminal adaptation unit, in order to ensure that the terminal adaptation unit can correctly identify and synchronize the cyclic prefix in the signal, thereby ensuring correct data decoding and resistance to multipath interference, further, as an optional implementation method, refer to... Figure 2 As shown, Figure 2 A detailed flowchart illustrating the process of sending the current cyclic prefix length to the terminal adaptation unit, specifically step S140 includes:

[0074] In step S210, the current cyclic prefix length is encoded to obtain a cyclic prefix pattern identifier.

[0075] In step S220, the prefix mode identifier is stored in the physical frame header, and the physical frame header and the new orthogonal frequency division multiplexing symbol are sent to the terminal adaptation unit.

[0076] In this embodiment, the physical frame header includes a pilot group, a prefix mode identifier, and a distance check code. The pilot group can consist of a specific sequence and is used to help the terminal adaptation unit perform time and frequency synchronization and channel estimation, ensuring accurate demodulation of communication data. The distance check code can be used to verify parameters related to transmission distance in the physical layer, such as signal attenuation and delay, or to perform basic verification of the integrity of the frame header, ensuring the reliability of data transmission.

[0077] After obtaining the current cyclic prefix length and adjusting the prefix length of the orthogonal frequency division multiplexing (OFDM) symbols accordingly, the on-board processing unit can encode the current cyclic prefix length, converting it into a 3-bit mode identifier. This 3-bit mode identifier serves as the cyclic prefix mode identifier. After obtaining the cyclic prefix mode identifier, it can store it in the physical frame header and transmit the new OFDM symbols and the physical frame header to the terminal adaptation unit via the satellite downlink.

[0078] The terminal adaptation unit stores a mapping table between cyclic prefix mode identifiers and cyclic prefix lengths. Upon receiving a new orthogonal frequency division multiplexing (OFDM) symbol and a physical frame header, the terminal adaptation unit parses the physical frame header to obtain the cyclic prefix mode identifier and then looks up the mapping table to determine the current cyclic prefix length corresponding to the cyclic prefix mode identifier. After determining the current cyclic prefix length, the terminal adaptation unit can use this length to remove the prefix length of the new OFDM symbol, thus obtaining the OFDM symbol and, consequently, the communication data.

[0079] In this embodiment, by encoding the current cyclic prefix length and generating a cyclic prefix mode identifier, the terminal adaptation unit can immediately identify the prefix length used when receiving the physical frame header, and perform precise synchronization based on the prefix length used, thereby avoiding synchronization failure, data loss, or incorrect decoding due to prefix length mismatch.

[0080] It is worth noting that there is high-speed relative motion between the on-board processing unit and the terminal adaptation unit; for example, the speed of a low-Earth orbit satellite can reach 7.8 km / s. Therefore, a significant Doppler frequency offset, i.e., signal frequency deviation, will occur between the on-board processing unit and the terminal adaptation unit. Simultaneously, the channel environment, such as ionospheric scintillation and multipath effects, will also change rapidly over time. If left unaddressed, this frequency offset will lead to signal demodulation errors in the terminal adaptation unit, and in severe cases, communication interruption. Therefore, to ensure effective communication between the on-board processing unit and the terminal adaptation unit, a dual-loop compensation mechanism can be implemented using a combined anti-frequency offset mechanism. Furthermore, as an optional implementation method, refer to... Figure 3 As shown, Figure 3 This is a flowchart illustrating the process of calculating the new cyclic prefix length using the residual frequency offset, specifically following step S140:

[0081] In step S310, the relative speed between the terminal adaptation unit and the on-board processing unit is determined.

[0082] In step S320, the pre-compensation frequency offset is determined using the relative velocity.

[0083] In step S330, the frequency of the pilot signal is adjusted using the pre-compensated frequency offset, and the pilot signal with the adjusted frequency is sent to the terminal adaptation unit so that the terminal adaptation unit can determine the residual frequency offset based on the pilot signal with the adjusted frequency. The terminal adaptation unit encapsulates the residual frequency offset into a feedback report and sends the feedback report to the on-board processing unit.

[0084] In step S340, a feedback report sent by the terminal adaptation unit is received.

[0085] In step S350, the feedback report is sent to the ground control center so that the ground control center can parse the feedback report to obtain the residual frequency offset, determine a new subcarrier spacing based on the residual frequency offset and the current subcarrier spacing, calculate a new cyclic prefix length based on the new subcarrier spacing, and send the new cyclic prefix length to the on-board processing unit.

[0086] In step S360, the new cyclic prefix length is received and sent to the terminal adaptation unit.

[0087] Specifically, refer to Figure 4 As shown, Figure 4 This is a flowchart illustrating the dual-ring compensation process. The on-board processing unit can calculate the relative velocity between the terminal adaptation unit and the on-board processing unit based on its own velocity vector and the velocity vector of the terminal adaptation unit. V rel Represents relative velocity. This represents the velocity vector of the onboard processing unit. θ represents the velocity vector of the terminal adaptation unit, and θ represents the angle between the relative velocity directions of the line connecting the on-board processing unit and the terminal adaptation unit.

[0088] After obtaining the relative velocity between the terminal adaptation unit and the on-board processing unit, the pre-compensated frequency offset can be calculated using the relative velocity. Δf pre This indicates the pre-compensated frequency offset. After obtaining the pre-compensated frequency offset, frequency pre-compensation is performed on the pilot signal before transmission, with a compensation amount of Δf. pre This means that the transmitting end pre-compensates, and after pre-compensating the pilot signal frequency, the pilot signal can be sent to the terminal adaptation unit through the satellite downlink.

[0089] After receiving the pilot signal from the on-board processing unit, the terminal adaptation unit calculates the phase difference between adjacent pilot signals, i.e. Represents the phase difference, y t1 y represents the sampled value of the pilot signal at time t1. t2 Let represent the sampled value of the pilot signal at time t2, and ∠ represent the complex phase angle. After obtaining the phase difference, the residual frequency offset can be calculated using the phase difference, i.e. Δf res The residual frequency offset is represented, which is the frequency offset based on the orbit prediction. t2-t1 represents the time interval between two adjacent pilot signal receptions.

[0090] After determining the residual frequency offset, the terminal adaptation unit can encapsulate the residual frequency offset and channel quality signals such as signal-to-noise ratio into a feedback report, and send the feedback report to the on-board processing unit via the uplink, which is the receiver pilot feedback. After receiving the feedback report, the on-board processing unit sends the feedback report to the ground control center via the downlink.

[0091] After receiving the feedback report, the ground control center analyzes it to obtain the residual frequency offset. Based on this residual frequency offset and the current subcarrier spacing, a new subcarrier spacing can be determined. Indicates the new subcarrier spacing. This indicates the current subcarrier spacing, which is also the dynamically adjusted subcarrier spacing. The new subcarrier spacing range is...

[0092] After determining the new subcarrier spacing range, the ground control center can use the new subcarrier spacing to calculate the new cyclic prefix length, i.e. T cp T represents the new cyclic prefix length. max represents the maximum delay spread, and k represents the protection factor, with a value range of [0.2, 0.3]. After calculating the new cyclic prefix length, the ground control center can send the new cyclic prefix length to the onboard processing unit via the uplink. Upon receiving the new cyclic prefix length, the onboard processing unit sends the new cyclic prefix length to the ground control center via the downlink, which is the CP length synchronization update.

[0093] In this embodiment, the onboard processing unit estimates the frequency offset using relative velocity and pre-compensates the pilot signal. The terminal adaptation unit determines the residual frequency offset based on the received pilot signal after frequency adjustment. The ground control center adjusts the subcarrier spacing in real time based on the residual frequency offset; that is, the spacing is increased to resist interference when the frequency offset is large, and the spacing is decreased to improve spectral efficiency when the frequency offset is small. Simultaneously, the cyclic prefix length is adjusted to match the current channel delay spread, effectively eliminating inter-symbol interference. This is particularly suitable for complex scenarios such as rainfall and multipath propagation, thereby significantly reducing demodulation errors caused by frequency offset. Furthermore, this embodiment uses a closed-loop feedback mechanism of terminal → onboard → ground → onboard → terminal to achieve real-time adaptive adjustment. Even if the satellite orbit changes, the terminal adaptation unit moves, or the channel changes abruptly, it can respond quickly and maintain the stability of the communication link.

[0094] Understandably, satellite communications face complex interference such as space radiation, atmospheric attenuation, and Doppler shift, and channel quality may change rapidly over time. Bit Error Rate (BER) directly reflects the probability of data transmission errors and is a key indicator of link reliability. Therefore, to promptly detect transmission anomalies, such as sudden interference leading to an increased BER, and to ensure effective communication between the onboard processing unit and the terminal adaptation unit, further, as an optional implementation method, refer to... Figure 5 As shown, Figure 5 This is a flowchart illustrating the process of updating the real-time channel variation coefficients based on the bit error rate. Specifically, after step S140, the process further includes:

[0095] In step S510, the bit error rate sent by the terminal adaptation unit is received.

[0096] In step S520, the bit error rate is sent to the ground control center so that after receiving the bit error rate, the ground control center determines whether the bit error rate is greater than a preset bit error rate. If the bit error rate is greater than the preset bit error rate, the long short-term memory model is optimized using historical channel data and current channel data to obtain new real-time channel change coefficients. The new real-time channel change coefficients are then converted into special subframe configuration indexes and sent to the on-board processing unit.

[0097] In step S530, the special subframe configuration index is received.

[0098] In step S540, the new channel real-time change coefficient is determined based on the special subframe configuration index.

[0099] In this embodiment, the bit error rate (BER) is a core indicator for measuring the quality of a communication link. It describes the proportion of erroneous bits during data transmission and represents the ratio between the number of erroneous bits received by the terminal adaptation unit and the total number of received bits.

[0100] Specifically, refer to Figure 6 As shown, Figure 6This is a flowchart illustrating the dynamic cyclic prefix adjustment process. After detecting the communication distance and radial velocity difference, the onboard processing unit can calculate the theoretical CP length, i.e., the current cyclic prefix length, using a formula. Once the current cyclic prefix length is obtained, the onboard processing unit can query the locally stored Level 3 CP mode table (Table 1) to determine the current communication scenario. After determining the current communication scenario, a frame header configuration identifier, i.e., a cyclic prefix mode identifier, is generated. This identifier is inserted into the physical frame header, and the cyclic prefix length is adjusted using the current cyclic prefix length to obtain a new cyclic prefix symbol. The new cyclic prefix symbol and physical frame header are then sent to the terminal adaptation unit. Upon receiving the new cyclic prefix symbol and physical frame header, the terminal adaptation unit can determine the current cyclic prefix length from the physical frame header and remove the prefix length of the new cyclic prefix symbol using the current cyclic prefix length to obtain the communication data. After receiving the communication data, the terminal adaptation unit can calculate the bit error rate (BER) by comparing known test sequences or utilizing the error correction statistics of the forward error correction (FEC) decoder, i.e., real-time evaluation of the BER. After calculating the BER, the terminal adaptation unit sends it to the on-board processing unit via the uplink. Upon receiving the BER from the terminal adaptation unit, the on-board processing unit sends it to the ground control center via the downlink. Upon receiving the BER, the ground control center determines whether it exceeds a preset BER. If the BER exceeds the preset BER, it optimizes the long short-term memory model using historical and current channel data to obtain new real-time channel change coefficients. These new real-time channel change coefficients are then converted into special subframe configuration indexes and sent to the on-board processing unit via the uplink. In other words, if the BER > a threshold, coefficients α and β are updated. Upon receiving the special subframe configuration index, the on-board processing unit can look up the mapping table to determine the new real-time channel change coefficients.

[0101] In this embodiment, when the communication channel is susceptible to environmental interference and the movement of the terminal adaptation unit, leading to fluctuations in the bit error rate, this embodiment calculates the bit error rate in real time through the terminal adaptation device, enabling timely detection of transmission quality degradation and preventing fault accumulation. Simultaneously, the ground control center employs a Long Short-Term Memory (LSTM) model, combining historical channel data with current real-time data for optimization. Because the LSM model excels at capturing long-term dependencies in time-series data, it can more accurately predict channel change trends, generating "real-time channel change coefficients" that better reflect the actual channel conditions than traditional static configurations, thereby reducing the bit error rate. Furthermore, when the ground control center transmits the new real-time channel change coefficients to the onboard processing unit, it converts the complex coefficients into a special subframe configuration index, effectively encoding and compressing the optimization results. This method reduces the amount of data transmitted between the satellite and ground, lowering communication latency and bandwidth usage. Simultaneously, the onboard processing unit can quickly parse the index and apply the configuration, improving response speed. In addition, the entire process forms a closed loop of "monitoring-analysis-adjustment-re-monitoring". When the bit error rate exceeds the standard, optimization is triggered. The optimized configuration is distributed through an index, and the on-board processing unit applies it and monitors the effect again. If it still does not meet the standard, it can be repeated iteratively. By dynamically optimizing the channel parameters of the satellite communication link, the transmission reliability problem caused by the complex and ever-changing channel environment between the satellite and the ground terminal is solved, and stable transmission quality is maintained.

[0102] It is worth mentioning that in satellite communication systems, both the master satellite and slave satellites can transmit data with the terminal adapter unit, and data can also be transmitted between the master satellite and slave satellites. When a slave satellite transmits data to the terminal adapter unit, or a master satellite transmits data to a slave satellite, to address the extended latency between the slave satellite and the terminal adapter unit, or between the master satellite and the slave satellite, and to avoid the cumulative latency across multiple links, as an optional implementation, when transmitting data between the slave satellite and the terminal adapter unit, or between the master satellite and the slave satellite, the cyclic prefix length can be scaled according to the relative distance between the slave satellite and the master satellite. In scenarios where data is transmitted from satellite to terminal adapters, CP slave CP represents the cyclic prefix length during data communication between the satellite and the terminal adapter unit. master This represents the cyclic prefix length during data communication between the main satellite and the terminal adapter unit, i.e., the current cyclic prefix length, d. slave d represents the relative distance between the satellite and the terminal adapter unit. master This indicates the relative distance between the master satellite and the terminal adapter unit; in scenarios where the master satellite and slave satellite transmit data, CP... slave d represents the length of the cyclic prefix during data communication between the satellite and the master satellite. slaveThis indicates the relative distance between the satellite and the main satellite.

[0103] Furthermore, as an optional implementation, this embodiment also provides a space-ground cooperative system, referring to... Figure 7 As shown, Figure 7 This is a schematic diagram of the framework of the space-ground collaborative system. Figure 7 In the process, the onboard processing unit calculates the current cyclic prefix length using the CP calculation engine based on real-time range and radial velocity difference feedback. After obtaining the current cyclic prefix length, it generates a special subframe configuration index corresponding to the current cyclic prefix length through a dynamic frame generator, inserts the special subframe configuration index into the physical frame header, and adjusts the prefix length of the orthogonal frequency division multiplexing (OFDM) symbol using the current cyclic prefix length through the OFDM modulation module to obtain a new OFDM symbol. The new OFDM symbol and physical frame header are then sent to the terminal adaptation unit. Upon receiving the new OFDM symbol and physical frame header, the terminal adaptation unit analyzes the physical frame header to obtain the current cyclic prefix length, performs CP configuration based on the current cyclic prefix length, and then removes the prefix length of the new OFDM symbol using the current cyclic prefix length through the OFDM modulation module to obtain the communication data. After receiving communication data, the terminal adaptation unit can calculate the bit error rate (BER) and send it to the ground control center. Upon receiving the BER, the ground control center determines whether to update the real-time channel variation coefficient. If the BER is updated, the new coefficient is used as an adjustment strategy, which is then sent to the onboard processing unit and the terminal adaptation unit. Alternatively, as another optional implementation, after determining the pre-compensated frequency offset based on the relative velocity, the onboard processing unit adjusts the frequency of the pilot signal using the pre-compensated frequency offset and sends the adjusted pilot signal to the terminal adaptation unit. Upon receiving the adjusted pilot signal, the terminal adaptation unit determines the residual frequency offset and sends it to the ground control center. Upon receiving the residual frequency offset, the ground control center uses the residual frequency offset and the current subcarrier spacing to determine a new subcarrier spacing, calculates a new cyclic prefix length based on the new spacing, and sends this new cyclic prefix length as a strategy to the onboard processing unit and the terminal adaptation unit.

[0104] To facilitate a better understanding of this embodiment, specific examples are provided below.

[0105] Example 1: LEO satellite communication with ground station

[0106] The communication distance between the LEO satellite and the ground station is 1200km. Through the aforementioned operations, the current cyclic prefix length was calculated to be 8.2μs, determining the communication scenario to be a mid-range communication scenario. The frame structure is a normal subframe (normal cyclic prefix) + a special subframe configuration index (current cyclic prefix length), with the special subframe configuration index being "101". Based on this, when the LEO satellite communicates with the ground station, the spectrum utilization is improved by 18%, and the bit error rate is reduced to 10%. -7 the following.

[0107] Example 2: Communication between GEO satellites and deep space probes

[0108] The communication distance between the GEO satellite and the deep space probe is 380,000 km. Through the aforementioned operations, the current cyclic prefix length is calculated to be 42.5 μs, and the communication scenario is determined to be a long-distance communication scenario. The frame structure is a fully extended cyclic prefix subframe, and the subcarrier spacing is compressed to 60 kHz. Based on this, the latency fluctuation between the GEO satellite and the deep space probe during communication is reduced from ±5 ms to ±0.1 ms.

[0109] In a second aspect, the present invention provides a communication device for an on-board processing unit, the communication device comprising:

[0110] The acquisition module is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center; wherein, the real-time channel change parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit, and the real-time channel change coefficients include a distance delay coefficient and a velocity coefficient;

[0111] The determination module is used to determine the current cyclic prefix length based on the real-time channel change parameters and the real-time channel change coefficients;

[0112] The modification module is used to modify the prefix length of the orthogonal frequency division multiplexing symbol using the current cyclic prefix length, so as to obtain a new orthogonal frequency division multiplexing symbol;

[0113] The sending module is used to send the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new orthogonal frequency division multiplexing symbol based on the current cyclic prefix length to obtain communication data.

[0114] Thirdly, this embodiment also provides a communication system, including: a satellite-ground cooperative system, one or more processors, a memory, and one or more programs, wherein the satellite-ground cooperative system includes an on-board processing unit, a ground control center, and a terminal adaptation unit.

[0115] The ground control center is used to send real-time channel variation coefficients to the on-board processing unit;

[0116] The terminal adaptation unit is used to receive the current cyclic prefix length sent by the on-board processing unit, and remove the prefix length of the new orthogonal frequency division multiplexing symbol according to the current cyclic prefix length to obtain communication data;

[0117] The on-board processing unit is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center. Based on the real-time channel change parameters and real-time channel change coefficients, it determines the current cyclic prefix length, modifies the prefix length of the orthogonal frequency division multiplexing (OFDM) symbol using the current cyclic prefix length, obtains a new OFDM symbol, and sends the current cyclic prefix length and the new OFDM symbol to the terminal adaptation unit.

[0118] The one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for implementing any of the preceding communication methods.

[0119] As a fourth aspect of the present invention, a computer-readable medium is provided having a computer program stored thereon, which, when executed by a processor, implements the communication method provided in the first aspect of the present disclosure.

[0120] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. Accordingly, the computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can implement the methods of any of the above embodiments. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0121] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A communication method, characterized in that, For on-board processing units, including: The system acquires real-time channel change parameters and real-time channel change coefficients sent by the ground control center; wherein, the real-time channel change parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit, and the real-time channel change coefficients include a distance delay coefficient and a velocity coefficient. The current cyclic prefix length is determined based on the real-time channel change parameters and the real-time channel change coefficients. The prefix length of the orthogonal frequency division multiplexing symbol is modified using the current cyclic prefix length to obtain a new orthogonal frequency division multiplexing symbol; The current cyclic prefix length and the new orthogonal frequency division multiplexing (OFDM) symbol are sent to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new OFDM symbol based on the current cyclic prefix length to obtain communication data.

2. The communication method according to claim 1, characterized in that, The step of determining the current cyclic prefix length based on the real-time channel change parameters and the real-time channel change coefficients includes: The current cyclic prefix length is determined based on the real-time channel change parameters, the real-time channel change coefficients, and Formula 1. Formula 1 includes: Among them, CP length The current loop prefix length is represented by α, the distance delay coefficient by β, the velocity coefficient by d, the communication distance by |Δv|, and the radial velocity difference by f. c Indicates carrier frequency, c represents the speed of light, and Base... CP Indicates the base CP length.

3. The communication method according to claim 1, characterized in that, The step of sending the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit includes: The current cyclic prefix length is encoded to obtain the cyclic prefix pattern identifier; The prefix mode identifier is stored in the physical frame header, and the physical frame header and the new orthogonal frequency division multiplexing symbol are sent to the terminal adaptation unit.

4. The communication method according to claim 3, characterized in that, The physical frame header includes a pilot group, a prefix mode identifier, and a distance check code.

5. The communication method according to claim 1, characterized in that, After sending the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, the method further includes: Determine the relative speed between the terminal adaptation unit and the on-board processing unit; The pre-compensation frequency offset is determined using the relative velocity. The frequency of the pilot signal is adjusted using the pre-compensated frequency offset, and the adjusted pilot signal is sent to the terminal adaptation unit so that the terminal adaptation unit can determine the residual frequency offset based on the adjusted pilot signal. The terminal adaptation unit encapsulates the residual frequency offset into a feedback report and sends the feedback report to the on-board processing unit. Receive feedback reports sent by the terminal adaptation unit; The feedback report is sent to the ground control center so that the ground control center can parse the feedback report to obtain the residual frequency offset, determine a new subcarrier spacing based on the residual frequency offset and the current subcarrier spacing, calculate a new cyclic prefix length based on the new subcarrier spacing, and send the new cyclic prefix length to the on-board processing unit. The new cyclic prefix length is received and sent to the terminal adaptation unit.

6. The communication method according to claim 4, characterized in that, The new subcarrier spacing range is This indicates the new subcarrier spacing.

7. The communication method according to claim 1, characterized in that, After sending the current cyclic prefix length and the new orthogonal frequency division multiplexing (OFDM) symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new OFDM symbol based on the current cyclic prefix length to obtain communication data, the process further includes: Receive the bit error rate sent by the terminal adaptation unit; The bit error rate is sent to the ground control center so that after receiving the bit error rate, the ground control center determines whether the bit error rate is greater than a preset bit error rate. If the bit error rate is greater than the preset bit error rate, the long short-term memory model is optimized using historical channel data and current channel data to obtain new real-time channel change coefficients. The new real-time channel change coefficients are then converted into special subframe configuration indexes and sent to the on-board processing unit. Receive the special subframe configuration index; The new real-time channel change coefficients are determined based on the special subframe configuration index.

8. A communication device, characterized in that, For on-board processing units, including: The acquisition module is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center; wherein, the real-time channel change parameters include the communication distance between the on-board processing unit and the terminal adaptation unit, and the radial velocity difference between the terminal adaptation unit and the on-board processing unit, and the real-time channel change coefficients include a distance delay coefficient and a velocity coefficient; The determination module is used to determine the current cyclic prefix length based on the real-time channel change parameters and the real-time channel change coefficients; The modification module is used to modify the prefix length of the orthogonal frequency division multiplexing symbol using the current cyclic prefix length, so as to obtain a new orthogonal frequency division multiplexing symbol; The sending module is used to send the current cyclic prefix length and the new orthogonal frequency division multiplexing symbol to the terminal adaptation unit, so that the terminal adaptation unit removes the prefix length of the new orthogonal frequency division multiplexing symbol based on the current cyclic prefix length to obtain communication data.

9. A communication system, characterized in that, It includes a space-ground collaborative system, one or more processors, a memory, and one or more programs, wherein the space-ground collaborative system includes an on-board processing unit, a ground control center, and a terminal adaptation unit. The ground control center is used to send real-time channel variation coefficients to the on-board processing unit; The terminal adaptation unit is used to receive the current cyclic prefix length sent by the on-board processing unit, and remove the prefix length of the new orthogonal frequency division multiplexing symbol according to the current cyclic prefix length to obtain communication data; The on-board processing unit is used to acquire real-time channel change parameters and real-time channel change coefficients sent by the ground control center. Based on the real-time channel change parameters and real-time channel change coefficients, it determines the current cyclic prefix length, modifies the prefix length of the orthogonal frequency division multiplexing (OFDM) symbol using the current cyclic prefix length, obtains a new OFDM symbol, and sends the current cyclic prefix length and the new OFDM symbol to the terminal adaptation unit. The one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing the communication method according to any one of claims 1 to 7.

10. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the communication method according to any one of claims 1 to 7.

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